Related papers: Light scalar mesons in the soft-wall model of AdS/…
Attention is paid to the production mechanisms of light scalars that reveal their nature. We reveal the chiral shielding of the \sigma(600) meson. We show that the kaon loop mechanism of the \phi radiative decays, ratified by experiment,…
It is shown that the recent data on the $K^0_S K^+$ correlation in Pb-Pb interactions agree with the data on the $\gamma\gamma\to\eta\pi^0$ and $\phi\to\eta\pi^0\gamma$ reactions and support the four-quark model of the $a_0(980)$ meson. It…
We present results of dynamical simulations with 2 flavours of degenerate Wilson twisted mass quarks at maximal twist in the range of pseudo scalar masses from 300 to 550 MeV. The simulations are performed at one value of the lattice…
The QCD sum rules in the large-$N_c$ limit for the light non-strange vector, axial and scalar mesons are considered assuming a string-like linear spectrum for the radially excited states. We propose a improved method for combined analysis…
We present a new chiral quark model for mesons involving a heavy and a light (anti-) quark. The model relates various combinations of a quark - meson coupling constant and loop integrals to physical quantities. Then, some quantities may be…
Non-leptonic D meson decays may provide a reliable testbed for the multiquark interpretation of light scalar mesons. In this letter we consider D_s decay and show that a 4-quark f_0(980) meson could induce a decay pattern, which is…
We study $\bar qq$-hybrid mixing for the light vector mesons and $\bar qq$-glueball mixing for the light scalar mesons in Monte-Carlo based QCD Laplace sum rules. By calculating the two-point correlation function of a vector $\bar…
QCD Laplace sum-rules for light-quark I=0,1 scalar currents are used to investigate candidates for the lightest $q\bar q$ scalar mesons. The theoretical predictions for the sum-rules include instanton contributions which split the…
I argue that in certain chiral gauge theories composite scalars associated with chiral symmetry breaking can be light (i.e. lighter than naive scaling from QCD would suggest) without any fine-tuning. These scalars will be even lighter in…
$B_{(s)}$ semi-leptonic decays to the light scalar meson, $B_{(s)}\to S l\bar{\nu}_l, S l \bar{l}\,\,(l=e,\mu,\tau)$, are investigated in the QCD light-cone sum rules (LCSR) with chiral current correlator. Having little knowledge of…
In the SU(3) symmetry limit, the ratio $R\equiv\frac{{\cal B}(D^+\to f_0l^+\nu)+ {\cal B}(D^+\to \sigma l^+\nu)}{{\cal B}(D^+\to a_0^0l^+\nu)}$ is equal to 1 if the scalar mesons are $\bar qq$ states, while it is 3 if these mesons are…
Dilepton decays of pseudoscalar mesons have been drawing particular interest, thanks to their sensitivity to both the QCD dynamics at low energy and also signals beyond the Standard Model. In this context, we shortly review our recent study…
The nonleptonic weak decays of charmed mesons into a scalar meson and a pseudoscalar meson are studied. The scalar mesons under consideration are $\sigma$ [or $f_0(600)$], $\kappa$, $f_0(980)$, $a_0(980)$ and $K^*_0(1430)$. A consistent…
We propose a general class of five-dimensional soft-wall models with AdS metric near the ultraviolet brane and four-dimensional Poincar\'e invariance, where the infrared scale is determined dynamically. A large UV/IR hierarchy can be…
The mixing angle, mass and couplings of the light scalar mesons $f_0(500)$ and $f_0(980)$ are calculated in the framework of QCD two-point sum rule approach by assuming that they are tetraquarks with diquark-antidiquark structures. The…
The light scalar mesons a_0/f_0(980) are being investigated at COSY-Juelich by detecting the strong decays into K-K-bar and pi-eta/pi-pi as well as radiative decays into vector mesons. Selected results are discussed with emphasis on recent…
The following topics are considered. 1) Confinement, chiral dynamics, and light scalar mesons. 2) Chiral shielding of the $\sigma(600)$. 3) The $\phi$ meson radiative decays about nature of light scalar resonances. 4) The $J/\psi$ decays…
We study the light scalar mesons a_0(980) and kappa using N_f = 2+1+1 flavor lattice QCD. In order to probe the internal structure of these scalar mesons, and in particular to identify, whether a sizeable tetraquark component is present, we…
We compute pseudoscalar meson masses and decay constants in partially quenched QCD with three dynamical flavors of improved staggered quarks. Fitting the lattice data to staggered chiral perturbation theory forms and extrapolating in quark…
The ${q}\bar{q}$ spectrum is studied within a chiral constituent quark model. It provides with a good fit of the available experimental data from light (vector and pseudoscalar) to heavy mesons. The new $D$ states measured at different…